Apparatus and method for mounting components on a substrate

ABSTRACT

The invention relates to an apparatus for mounting components on a substrate. The apparatus comprises a bond head with a component gripper, a first drive system for moving a carrier over relatively long distances, a second drive system which is attached to the carrier for moving the bond head back and forth between a nominal working position and a stand-by position, a drive attached to the bond head for rotating the component gripper or a rotary drive for rotating the substrate about an axis, at least one substrate camera attached to the carrier and at least one component camera. Either the second drive system is also designed to perform high-precision correction movements with the bond head, or a third drive system is provided to perform high-precision correction movements with the substrate. At least one reference mark is attached to the bond head or the component gripper.

PRIORITY CLAIM

The present application is a divisional of U.S. patent application Ser.No. 15/947,571 filed Apr. 6, 2018 in the name of inventors Andreas Mayr,Hugo Pristauz, Hubert Selhofer and Norbert Bilewicz and entitled“Apparatus and method for mounting components on a substrate,” whichclaims foreign priority under 35 U.S.C § 119 from Swiss Application No.00575/17 filed Apr. 28, 2017, the disclosure of which is hereinincorporated by reference.

FIELD OF THE INVENTION

The invention relates to an apparatus for mounting components on asubstrate, typically electronic or optical components, in particularsemiconductor chips and flip chips, on a substrate. In the field, themounting is also referred to as bonding process or assembly process.

BACKGROUND OF THE INVENTION

Apparatuses of this type are particularly used in the semiconductorindustry. Examples of such apparatuses are Die Bonders or Pick and Placemachines, with which components in the form of semiconductor chips, flipchips, micromechanical, micro-optical and electro-optical components,and the like are deposited on substrates such as leadframes, printedcircuit boards, ceramics, etc. and bonded. The components are picked upby a bond head at a removal location, in particular sucked in, moved toa substrate location and deposited at a precisely defined position onthe substrate. The bond head is part of a Pick and Place system, whichenables movement of the bond head in at least three space directions. Inorder to enable the component to be positioned accurately on thesubstrate, both the exact position of the component gripped by the bondhead with respect to the positioning axis of the bond head and the exactposition of the substrate place must be determined.

Mounting devices available on the market achieve in the best case apositioning accuracy of 2 to 3 micrometers with a standard deviation of3 sigma.

SHORT DESCRIPTION OF THE INVENTION

The object of the invention is to develop an apparatus, which achieves ahigher placement accuracy compared to the state of the art.

The apparatus according to the invention comprises a bond head with acomponent gripper, a first drive system for moving a carrier overrelatively long distances, a second drive system attached to the carrierfor moving the bond head back and forth between a nominal workingposition and a stand-by position, a drive attached to the bond head forrotating the component gripper or a rotary drive for rotating thesubstrate about an axis running perpendicularly to the substratesurface, at least one substrate camera attached to the carrier and atleast one component camera. The bond head or the component grippercontains at least one reference mark used by both the at least onecomponent camera and the at least one substrate camera to determine theposition of the component relative to the bond head or the position ofthe bond head relative to the substrate location, respectively. Thesubstrate contains at least one substrate mark and the componentcontains at least one component mark or a structure suitable to serve ascomponent mark.

The first drive system serves to move the bond head over relatively longdistances with relatively low positioning accuracy. The second drivesystem serves to move the bond head back and forth between the nominalworking position and the stand-by position. In the nominal workingposition, the bond head covers the substrate mark(s) attached to thesubstrate and is therefore temporarily moved to the stand-by positionwhere the bond head no longer covers the substrate mark(s) so that thesubstrate camera(s) can take an image of the substrate mark(s). Thesecond drive system preferably serves also to move the bond head overrelatively small distances with very high positioning accuracy, i.e. toperform high-precision correction movements of the bond head.Alternatively, a third drive system can be provided to performhigh-precision correction movements of the substrate.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent invention and, together with the detailed description, serve toexplain the principles and implementations of the invention. The figuresare not to scale. In the drawings:

FIG. 1 schematically shows a first embodiment of an apparatus formounting components on a substrate according to the invention,

FIG. 2 schematically shows a second embodiment of an apparatus formounting components on a substrate according to the invention, and

FIGS. 3-5 show snapshots taken during the assembly process according tothe invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically shows a first embodiment of an apparatus formounting components 1 on a substrate 2 according to the invention. Thesubstrates 2 contain at least one substrate mark 23 (FIG. 3). Thecomponents 1 are flip chips in particular, but also other semiconductorchips. The components 1 can also be electronic, optical orelectro-optical or any other components which are to be mounted with aprecision in the micrometer range or submicrometer range.

The mounting apparatus includes a bond head 3, a feeding unit 4 forsupplying the components 1, a device 5 for feeding and providing thesubstrates 2, and a first drive system 6 for a carrier 7 and a seconddrive system 8 for the bond head 3. The second drive system 8 isattached to the carrier 7. The apparatus further includes at least onecomponent camera 9 and at least one substrate camera 10. The substratecamera(s) 10 is/are attached to the carrier 7. The bond head 3 comprisesa component gripper 11, which is rotatable about an axis 12. In thefollowing, a component held by the bond head 3 is referred to ascomponent 1 a. The component gripper 11 is, for example, avacuum-operated suction element that sucks in a component 1.

The feeding unit 4 comprises, for example, a wafer table, which providesa plurality of semiconductor chips, and a flip device, which removes onesemiconductor chip after the other from the wafer table and provides itas flip chip for transfer to the bond head 3. The feeder unit 4 can alsobe a feeder unit that provides flip chips or other components one afterthe other for transfer to the bond head 3.

The bond head 3 or the component gripper 11 contains at least onereference mark 13 (FIG. 3), advantageously at least two reference marks13, so that both a displacement of the component 1 a held by thecomponent gripper 11 of the bond head 3 and a rotation of the component1 a from its set position can be detected and corrected. The referencemark(s) 13 is/are mounted on the bond head 3 or component gripper 11 insuch a way that it/they is/are visible in the image supplied by thecomponent camera 9 or the images supplied by the component cameras 9,when the bond head 3 is in the field of view of the component camera 9or the fields of view of the component cameras 9, and is/are visible inthe image supplied by the substrate camera 10 or the images supplied bythe substrate cameras 10, respectively, when the bond head 3 is in thefield of view of the substrate camera 10 or the fields of view of thesubstrate cameras 10, respectively. The reference mark (s) 13 is/are forexample formed as cross in bore(s) in the component gripper 11,preferably they are formed on a platelet of glass in the form ofstructures of chrome. Glass is transparent, so that the referencemark(s) 13 is/are seen from above as well as from below and thus by allcameras 9 and 10. Preferably, a glass with a very low coefficient ofthermal expansion is chosen. The thickness of the glass plate isadvantageously selected so that at a certain height of the bond head 3above the substrate 2, both the reference mark(s) 13 and the substratemark(s) 23 are imaged with sufficient sharpness in the image captured bythe substrate camera(s) 10, i.e. that both the reference mark(s) 13 andthe substrate mark(s) 23 are in the depth of field of the substratecamera(s) 10.

The first drive system 6 serves to transport the bond head 3 overrelatively long distances, namely from a component removal location,where the bond head 3 takes the component 1 to be mounted from thefeeder unit 4, to the substrate 2, where the bond head 3 places thecomponent 1 a on a substrate place of the substrate 2. The requirementsfor the position accuracy of the first drive system 6 are relativelymodest, a position accuracy of +/−10 μm is usually sufficient. The firstdrive system 6 is designed, for example, as a so-called “gantry” withtwo or more mechanically highly stable axes of motion, of which two axesof motion allow movements of the carrier 7 in two horizontal directionsrunning perpendicular to each other.

The up and down movements of the bond head 3 to remove a component 1from the feeder unit 4 and to place the component 1 a on the substrateplace of the substrate 2 can be done in different ways, for example

-   -   the first drive system 6 contains a third, highly stable axis of        motion for the up and down movement of the carrier 7,    -   the second drive system 8 contains an additional, high-precision        drive for the up and down movements of the bond head 3,    -   the bond head 3 contains a high-precision drive for up and down        movements of the component gripper 11, which is advantageously        supported by air or ball bearings.        The apparatus may contain only one, or two or all three of the        above axes of motion/drives for the up and down movements.

The second drive system 8 serves on the one hand to move the bond head 3into a stand-by position, as described below in more detail, and on theother hand to enable high-precision correction movements of the bondhead 3 in two different horizontal directions. The second drive system 8comprises a first drive for moving the bond head 3 along a firstdirection designated as u-direction and a second drive for moving thebond head 3 along a second direction designated as v-direction. Thedirections u and v run in horizontal direction and preferablyorthogonally to each other. The bond head 3 comprises, optionally, adrive 14 for the rotation of the component gripper 11 around the axis12. The device 5 for feeding and providing the substrates 2 may containa rotary drive 15 in order to rotate the substrate 2 about an axisrunning orthogonally to its surface in order to alternatively eliminateany angular errors in this manner.

The component camera 9 or the several component cameras 9 serve todetect the position of the component 1 a in relation to the position ofthe reference mark(s) 13. The substrate camera 10 or the substratecameras 10 serve to detect the position of the substrate place on whichthe component 1 a is to be placed, in relation to the position of thereference mark(s) 13. Each component camera 9 and each substrate camera10 comprises an image sensor 17 and an optics 18 (FIG. 3). The optics 18of the substrate camera(s) 10 comprises for example two deflectingmirrors 19.

The component camera(s) 9 is/are, for example, arranged stationary onthe apparatus and the bond head 3 is moved on its way from the componentremoval location to the substrate location above the component camera(s)9 and is preferably, but not necessarily, stopped for taking one or moreimages. The component camera(s) 9 can alternatively be attached to thecarrier 7. For example, either the component camera(s) 9 or the bondhead 3 is/are attached to the carrier 7 by means of a retractable andextendable swivel mechanism. The component camera(s) 9 or the bond head3, respectively, is then retracted into an image capture position whilemoving from the component removal location to the substrate location, sothat one or more images per component camera 9 can be captured duringthe move. For the removal of the component 1 from the feeder unit 4 andfor recording the images with the substrate camera(s) 10 and fordepositing the component 1 a, the component camera(s) 9 is/are extendedinto a stand-by position and the bond head 3 is extended into itsworking position.

The range of motion of the second drive system 8 is relatively small andeven very small compared to the range of motion of the first drivesystem 6. The second drive system 8 must be able to move the bond head 3from a nominal working position to the stand-by position in which thesubstrate marks 23 are not covered by the bond head 3 on the one hand,and on the other hand enable high-precision correction movements of thebond head 3 in two different horizontal directions. For this purpose, itis sufficient if the range of motion of the second drive system 8 isrelatively long in one horizontal direction and very short in the otherhorizontal direction. The range of motion in one direction is typicallya few ten millimeters, for example 20 mm or 30 mm or more, the range ofmotion in the other direction is typically (only) a few micrometers.

The nominal working position of the bond head 3 is a position thatdiffers only slightly from the final position which the bond head 3occupies in the last step of the assembly process. The accuracyrequirements for the nominal working position are relatively low, as anydeviation from the nominal working position is automatically compensatedlater in the assembly process.

The apparatus is configured, to lower the carrier 7 and/or the bond head3 and/or the component gripper 11 so far that the underside of thecomponent 1 a is located at an extremely low height of typically only50-200 μm above the substrate surface, and only then take an image ofthe substrate mark(s) 23 with the substrate camera(s) 10. In doing so,it is achieved that the only movement after the determination of theactual position of the component 1 a with respect to its set position onthe substrate place and after the execution of the high-precisioncorrection movements is only the lowering movement of the carrier 7and/or the bond head 3 and/or the component gripper 11 and that thisdistance is so short that any displacements in the u-direction and inthe v-direction during this lowering movement are in the submicrometerrange.

From the moment when the carrier 7 has reached its position in the areaof the substrate 2, the position of the substrate camera(s) 10 relativeto substrate 2 no longer changes. From this moment on, only the positionof the bond head 3 is changed, namely by means of the second drivesystem 8. The position of the reference mark(s) 13 can therefore bemonitored until the component 1 a is placed on the substrate 2 and anynew deviation from its set position that might occur during the finallowering phase of the component 1 a can be corrected. The components cantherefore be mounted with an unprecedented precision in thesubmicrometer range.

FIG. 2 illustrates a second embodiment of an apparatus according to theinvention, which is largely similar to the first embodiment, but withthe essential difference that the second drive system 8 is designed tomove the bond head 3 back and forth between the nominal working positionand the stand-by position, but not for the high-precision correctionmovements, and that the device 5 for feeding and providing thesubstrates 2 comprises a third drive system 16, which enableshigh-precision correction movements of the substrate 2 in at least twodifferent horizontal directions. The second drive system 8 can thereforeonly move the bond head 3 in a single direction running parallel to thesurface of the substrate 2. However, the second drive system 8 mayoptionally also be designed to raise and lower the bond head 3, i.e. tomove the bond head 3 in the direction running orthogonally to thesurface of the substrate 2. However, the high-precision correctionmovements in the plane running parallel to the surface of the substrate2 are performed in this embodiment by the third drive system 16. Thethird drive system 16 comprises a first drive for moving the substrate 2along a first direction, again designated as u-direction, and a seconddrive for moving the substrate 2 along a second direction, againdesignated as v-direction. The directions u and v run in horizontaldirection and preferably orthogonally to each other. The third drivesystem 16 may optionally also have a rotary drive 15 which allowsrotation of the substrate 2 about an axis perpendicular to the surfaceof substrate 2 in order to eliminate any angular errors.

With this apparatus a similarly high positioning accuracy can beachieved, even if during the last phase of the lowering of the component1 a, further correction movements of the substrate 2 that may still benecessary and that are carried out can no longer be checked for correctattainment.

The mounting of a component 1 is now explained in detail. The mountingmethod according to the invention comprises the following steps A to O.The steps can be in part executed in a different order.

-   A) with the component gripper 11 picking up a component 1 from the    feeding unit 4.-   B) with the first drive system 6 moving the carrier 7 to the    component camera 9 or the component cameras 9, so that the reference    mark or the reference marks 13 and the component 1 a are in the    field of vision of the component camera 9 or in the fields of vision    of the component cameras 9.

With a mounting apparatus, in which the component camera(s) 9 is/arearranged stationary, step B is carried out by: With the first drivesystem 6 moving the carrier 7 to the component camera 9 or the componentcameras 9. In a mounting apparatus in which the component camera(s) 9is/are attached to the carrier 7, step B is performed by: Moving thecomponent camera(s) 9 and the bond head 3 relative to each other into animage acquisition position.

-   C) take one or more images with the component camera 9 or the    component cameras 9.

The components 1 contain component marks 22 (FIG. 3) or other structuresthat can be used as component marks. The component marks 22 serve todetect the position of the component 1 a with respect to the referencemark(s) 13 with the required accuracy.

In a mounting apparatus in which the component camera(s) 9 is/areattached to the carrier 7, step C is followed by the step: Moving thecomponent camera(s) 9 and the bond head 3 relative to each other so thatthe bond head 3 is in its normal working position and, if necessary, thecomponent camera(s) 9 is in a stand-by position.

-   D) determining a first correction vector describing a deviation of    the actual position of the component 1 a from its set position with    respect to the reference mark(s) 13 on the basis of the image(s)    taken in the previous step.

The first correction vector comprises three components Δx₁, Δy₁ und Δφ₁,wherein Δx₁ designates the displacement of a reference point of thecomponent 1 a in a first direction designated as x₁-direction and Δy¹the displacement of the reference point of the component 1 a in a seconddirection designated as y₁-direction and Δφ₁ designates the rotation ofthe component 1 a around the reference point of the component 1 a withrespect to the reference mark(s) 13. The components Δx₁ und Δy₁ aregiven in pixel coordinates of the component camera(s) 9, the componentΔφ₁ is an angle. The first correction vector is a null vector, if thethe actual position of the component 1 a already corresponds to its setposition.

-   E) from the first correction vector calculating a first correction    movement.

The first correction movement comprises three correction values Δu₁, Δv₁and Δθ₁. The correction values Δu₁ and Δv₁ are calculated from thecomponents Δx₁, Δy₁ and Δθ₁. The correction value Δθ₁ is calculated fromthe angular error Δφ₁. The correction values Δu₁, Δv₁ and Δθ₁ are allgiven in machine coordinates of the corresponding drives. The correctionvalues Δu₁ and Δv₁ indicate the distances by which the second drivesystem 8 must move the bond head 3 (in the apparatus shown in FIG. 1) orthe third drive system 16 must move the substrate 2 (in the apparatusshown in FIG. 2) in the direction designated as the u-direction and inthe direction designated as the v-direction, and the correction valueΔθ₁ indicates the angle by which the drive 14 mounted on the bond head 3must rotate the component gripper 11 or the rotary drive 15 must rotatethe substrate 2 in order to eliminate the detected deviation of theactual position of the component 1 a from its set position relative tothe reference mark(s) 13.

-   F) with the first drive system 6 moving the carrier 7 to a position    above a substrate place of the substrate 2.-   G) lowering the carrier 7 to a height above the substrate 2 at which    the underside of the component 1 a held by the component gripper 11    is located at a predetermined distance D above the substrate place,    wherein the distance D is dimensioned such that both the reference    mark(s) 13 and the substrate mark(s) 23 lie in the depth of field of    the substrate camera(s) 10.

The distance D is typically about 50-200 micrometers, but is not limitedto these values. However, the distance D is so small that when thecomponent 1 a is subsequently lowered to the substrate place, usually nodisplacements of the component 1 a occur in the directions u and v thatlead to a significant position error.

-   H) with the second drive system 8 moving the bond head 3 to a    stand-by position.

Steps F, G and H can be executed one after the other or simultaneously,i.e. in parallel. The carrier 7 and thus also the substrate camera(s) 10attached to the carrier 7 are no longer moved during the following,remaining steps.

During steps A to G, the bond head 3 is usually in its nominal workingposition. The substrate camera(s) 10 does not see the substrate marks 23because the bond head 3 covers them. The position of the stand-byposition is selected such that the bond head 3 does not cover thesubstrate mark(s) 23.

-   I) with the substrate camera(s) 10 taking a first image, wherein the    field of view of the substrate camera 10 or each of the fields of    view of the substrate cameras 10 contains at least one substrate    mark 23 arranged on the substrate 2.-   J) with the second drive system 8 moving the bond head 3 to the    nominal working position in which the field of view of the substrate    camera 10 or each of the fields of view of the substrate cameras 10    contains at least one reference mark 13.-   K) with the substrate camera(s) 10 taking a second image.-   L) determining a second correction vector describing a deviation of    the actual position of the substrate place from its set position    with respect to the reference mark 13 or the reference marks 13,    respectively, using the first and second image or the first and    second images taken with the substrate camera(s) 10.

The second correction vector comprises three components Δx₂, Δy₂ undΔφ₂, wherein Δx₂ designates the displacement of the reference mark(s) 13in a first direction designated as x₂-direction and Δy₂ the displacementof the reference mark(s) 13 in a second direction designated asy₂-direction and Δφ₂ designates the rotation of the reference mark(s) 13with respect to the substrate place. The components Δx₂ und Δy₂ aregiven in pixel coordinates of the substrate camera(s) 10, the componentΔφ₂ is an angle.

-   M) from the second correction vector calculating a second correction    movement.

The second correction movement comprises three correction values Δu₂,Δv₂ and Δθ₂. The correction values Δu₂ and Δv₂ are calculated from thecomponents Δx₂, Δy₂ and Δφ₂. The correction value Δθ₂ is calculated fromthe angular error Δφ₂. The correction values Δu₂, Δv₂ and Δθ₂ are allgiven in machine coordinates of the corresponding drives. The correctionvalues Δu₂ and Δv₂ indicate the distances by which the second drivesystem 8 must move the bond head 3 (in the apparatus shown in FIG. 1) orthe third drive system 16 must move the substrate 2 (in the apparatusshown in FIG. 2) in the direction designated as the u-direction and inthe direction designated as the v-direction, and the correction value402 indicates the angle by which the drive 14 mounted on the bond head 3must rotate the component gripper 11 or the rotary drive 15 must rotatethe substrate 2 in order to eliminate the detected deviation of thereference mark(s) 13 of the bond head 3 from their set position inrelation to the substrate mark(s) 23 of the substrate 2.

-   N) executing the first and second correction movement.

The displacements by the correction values Δu₁, Δv₁, Δu₂ and Δv₂ arecarried out by the second drive system 8 for the apparatus according toFIG. 1 and by the third drive system 16 for the apparatus according toFIG. 2. The rotation by the correction values 401 and 402 is performedby the drive 14 or the rotary drive 15.

-   O) lowering the carrier 7 and/or the bond head 3 and/or the    component gripper 11 and place the component 1 a on the substrate    place.

If the mounting process is carried out with an apparatus according toFIG. 1, the method may optionally also include steps P to T, which arecarried out once or several times after step N:

-   P) taking an image with the substrate camera 10 or the substrate    cameras 10.-   Q) determining the actual position(s) of the reference mark(s) 13    using the image from the substrate camera 10 or the images from the    substrate cameras 10.-   R) with the first correction vector calculating corrected actual    position(s) of the reference mark 13 or the reference marks 13.

The first correction movement calculated in step E and executed in stepN for the bond head 3 and the component gripper 11 also shifts theposition of the reference mark(s) 13. This shift of the referencemark(s) 13 is deducted in step R, because the first correction movementhas nothing to do with the orientation with respect to the substrateposition.

-   S) determining a further correction vector describing the deviation    of the corrected actual position(s) of the reference mark(s) 13 from    its/their set position in relation to the substrate mark(s) 23.-   T) from the further correction vector calculating a further    correction movement for the bond head 3 and the component gripper    11.

The further correction movement for the bond head 3 and the componentgripper 11 comprises components Δu_(w), Δv_(w), which are given inmachine coordinates of the second drive system 8, and a componentΔθ_(w), which is an angular change in machine coordinates of the drive14 or the rotary drive 15.

-   U) with the second drive system 8 executing the further correction    movement for the bond head 3 and with the drive 14 or the rotary    drive 15 executing the further correction movement for the component    gripper 11.    until each component of the further correction vector is smaller    than a limit value assigned to the component.

The optional steps P to U serve to check whether the bond head 3 hasactually reached a position within the required accuracy after executingthe correction movements in step N, and if this is not the case,iteratively perform further correction steps until this is the case. Thedetected deviation must for each component be within the requiredaccuracy.

Step O of the method according to the invention can—especially in thecase of an apparatus according to FIG. 1—be supplemented by a monitoringin which the position of the reference mark(s) 13 is continuouslydetected by means of the substrate camera(s) 10 while the carrier 7 orthe bond head 3 or the component gripper 11 is lowered and stabilized bymeans of the second drive system 8 and the drive 14 or the rotary drive15, to avoid any change of the position of the reference mark(s) 13 andthus of the component 1 a. Step O can therefore be replaced by thefollowing step O1:

-   O1) lowering the carrier 7 and/or the bond head 3 and/or the    component gripper 11 and placing the component 1 a on the substrate    place, wherein the position of the reference mark(s) 13 is    continuously detected by means of the substrate camera 10 or the    substrate cameras 10 during the lowering and stabilized by means of    the second drive system 8 and, optionally, also by means of the    drive 14 or the rotary drive 15.

The substrate camera or substrate cameras 10 (including imageevaluation) and the second drive system 8, if necessary together withthe drive 14 or the rotary drive 15, form a closed loop axis of motion.

FIGS. 3 to 5 show snapshots taken during the mounting process accordingto the invention. The illustration is carried out using a mountingapparatus comprising a single component camera 9 and two substratecameras 10, the two substrate cameras 10 being attached to the carrier 7as mentioned above.

FIG. 3 shows a section of the mounting apparatus after step B. FIG. 4shows a section of the mounting apparatus during step I, when the bondhead 3 is in the standby position and the two substrate cameras 10 takethe first image. FIG. 5 shows a section of the mounting apparatus alittle bit later during step K, when the bond head 3 is in a position,in which each of the fields of view of the two substrate cameras 10contains at least one reference mark 13. The position of the substratecameras 10 relative to the substrate 2 has not changed during themovement of the bond head 3 from the state shown in FIG. 4 to the stateshown in FIG. 5. FIGS. 3 and 5 also illustrate the beam path 20 from thereference marks 13 to the image sensors 17 of the substrate cameras 10,while FIG. 4 illustrates the beam path 21 from the substrate marks 23 tothe image sensors 17 of the substrate cameras 10.

The placement of the substrate marks 23 on the substrates 2 is left tothe users of the mounting apparatus of the invention. A mountingapparatus with a single substrate camera 10 requires a differentarrangement of the reference mark(s) 13 on the bond head 3 or componentgripper 11 and the substrate mark(s) 23 on the substrate 2. Since thecomponents 1 are usually rectangular, the component mark(s) 22, thereference mark(s) 13 and the substrate mark(s) 23 are often arranged intwo diagonally opposite corners of the rectangle or in two adjacentcorners of the rectangle, as this achieves the highest accuracy.

In the embodiment shown in FIGS. 3 and 4, the bond head 3 moves from itsnominal working position to the stand-by position in a direction lyingin the drawing plane. However, it can also occur in a directionperpendicular to the drawing plane.

The term “component camera” is to be understood functionally, i.e. anoptical deflection system can form a component camera together with thesubstrate camera, as described in the published patent application US20170092613 (A), which is incorporated by reference into thisapplication. In such a case, a (single) camera and a first opticaldeflection system form together a first image detection system whichmakes it possible to take an image of the substrate location on whichthe component is to be mounted, and the camera, the first opticaldeflection system and a second optical deflection system form together asecond image detection system which makes it possible to take an imageof the underside of the component held by the bond head. The first imagedetection system corresponds to the substrate camera and the secondimage detection system corresponds to the component camera. The firstoptical deflection system may under certain circumstances also beomitted.

While embodiments and applications of this invention have been shown anddescribed, it would be apparent to those skilled in the art having thebenefit of this disclosure that many more modifications than mentionedabove are possible without departing from the inventive concepts herein.The invention, therefore, is not to be restricted except in the spiritof the appended claims and their equivalents.

1. An apparatus for mounting components on a substrate, comprising abond head with a component gripper, at least one reference mark, whichis arranged at the bond head or at the component gripper, a feeding unitconfigured to supply a component, a device configured to provide asubstrate, a first drive system configured to move a carrier, a seconddrive system, which is attached to the carrier, configured to move thebond head in one or several different directions, a drive attached tothe bond head and configured to rotate the component gripper about anaxis or a rotary drive configured to rotate the substrate about an axis,at least one substrate camera, and at least one component camera or atleast one optical deflection system which, together with the at leastone substrate camera, forms at least one component camera, wherein thesubstrate camera or the substrate cameras, respectively, is/are attachedto the carrier, the carrier and/or the bond head and/or the componentgripper is liftable and lowerable, the carrier is movable to the feedingunit by means of the first drive system, either the carrier is movableto the component camera(s) by means of the first drive system or thecomponent camera(s) is/are fixed to the carrier and svivelable inrelation to the bond head, so that the reference mark(s) and a componentgripped by the component gripper are in the field of view of thecomponent camera or in the fields of view of the component cameras, sothat the actual position of the component is detectable in relation tothe reference mark(s), the carrier is movable above a substrate place ofthe substrate by means of the first drive system and the bond head ismovable by means of the second drive system in a standby position, inwhich the field of view of the substrate camera or each of the fields ofview of the substrate cameras contains at least one substrate markarranged on the substrate, and the bond head is movable by means of thesecond drive system in a nominal working position, in which the field ofview of the substrate camera contains the reference mark(s) or each ofthe fields of view of the substrate cameras contains at least onereference mark, and wherein the carrier and/or the bond head and/or thecomponent gripper is lowerable to the extent that both the referencemark(s) and the at least one substrate mark are in the depth of field ofthe substrate camera(s).
 2. The apparatus according to claim 1, in whichthe second drive system is configured to move the bond head back andforth between the nominal working position and the stand-by position onthe one hand and to enable correction movements of the bond head on theother hand.
 3. The apparatus according to claim 1, in which thesubstrate camera or the substrate cameras and the second drive systemand the drive or the rotary drive form a closed loop axis of motion. 4.The apparatus according to claim 2, in which the substrate camera or thesubstrate cameras and the second drive system and the drive or therotary drive form a closed loop axis of motion.
 5. The apparatusaccording to claim 1, in which the second drive system is configured tomove the bond head back and forth between the nominal working positionand the stand-by position, and which comprises a third drive system,which allows correction movements of the substrate.
 6. The apparatusaccording to claim 1, in which the component camera or the componentcameras is/are fastened to the carrier and is/are movable or svivelablerelative to the bond head.